What sets Homo sapiens apart from other hominins? What enabled early Homo sapiens to survive, thrive and contribute to who we are today? For HERI’s Sahle, these are questions best answered by archaeological evidence from ~300,000–100,000 years ago.
“This is a time that unifies us all as humans, as a single species, in spite of all the differences highlighted in the more recent past,” he says. “And it all began here in Africa during the Middle Stone Age.”
The Middle Stone Age, or MSA, spans the period from about 300,000 years ago to around 25,000 years ago. This is when African archaeological evidence suggests our uniquely human culture, marked by the emergence of complex technological innovation, symbolic behaviour and language, evolved.
Unearthing that evidence and its evolutionary implications is at the heart of Sahle’s research. A Senior Lecturer in the Department of Archaeology at the University of Cape Town (UCT), he has worked on sites in Ethiopia, Kenya, South Africa, and Greece. These field experiences have helped Sahle to later develop an understanding of how environment, diet, technology, and other behaviours coevolved.
Sahle brings this broad archaeological research expertise, along with leadership skills honed both in the field in Ethiopia and in high-profile international institutions, to the board of HERI.
“Yonatan is also committed to diversifying and decolonising the discipline of human evolution, and raising the contributions and profiles of African researchers in particular. We’re honoured to have him,” says HERI Deputy Director Professor Rebecca Ackermann.
Destined to dig deeper
Sahle’s interest in human evolution began with his background in Ethiopia. Born in Addis Ababa, he had an early fascination with the history of his homeland.
Ethiopia is one of the oldest independent states in Africa, and one of only two African countries that avoided colonial rule. It is one of the earliest Christian nations on the continent, one of the first Muslim nations, and sits at the crossroads of cultural exchange between the Horn of Africa and Arabia.
“From my childhood, I was taught to love my history and my background. But I wanted to dig deeper and understand where it all began,” he says. This led to a fascination with archaeology that earned him a PhD from UCT, followed by postdoctoral training at the University of California, Berkley.
Along the way, he has discovered hominids, archaeological artefacts, and faunal remains from various time intervals. But Sahle isn’t driven by the eureka moments of finding evidence in the field. Instead, he looks at his work as contributing to the big picture of our past – one piece at a time.
“When I go to the field and look at an assemblage, that is fascinating enough for me. Every single piece in archaeology has a story to tell and whatever the amount, it contributes to the bigger picture of understanding the human past,” he says.
African paleoanthropological record
Sahle may be humble about his work, but he is excited about what he says is an air of change he’s bringing to UCT, where his diversity of experience is converging in new site explorations.
“We have a new site where, perhaps for the first time, we can investigate the hominin past in an integrated manner,” he says. “We are going to be able to ask how past environments influenced human technological innovation and hominin behaviour – and whether and how that influenced our biology.”
After several years of field exploration in Ethiopia’s Afar Rift, famous for its early hominin remains, Sahle has recently discovered sedimentary deposits that contain hominin, artefact, and faunal remains.
“The time interval my new field research project samples is very rare in the African paleoanthropological record,” Sahle remarks. He describes finding hominin remains preserving unique features, which his team – including Ackermann and HERI’s Dr Lauren Schroeder – are currently studying.
Other exciting finds from localities in this new research area include the remains of extinct species of hyaena and elephant, alongside stone tool technologies that document the Acheulean to MSA transition. Sahle announced the site discovery in 2019.
“Palaeoenvironmental dynamics across 500,000 to 300,000 years ago may have led to the emergence of our species and MSA technologies,” Sahle says.
While others have suggested this hypothesis earlier, Sahle and his colleagues are the first with the ability to test it. “There hasn’t been a temporally pertinent context with hominins, archaeology and fauna co-appearing together, until now,” he says, noting that they are currently refining the dating of the unique findings from their site.
On the shoulders of giants
Research isn’t the only air of change Sahle is bringing to UCT. His appointment to the Department of Archaeology, alongside HERI's Dr Vuyiswa Lupuwana, made it the first department in the Faculty of Science with a black staff majority.
Noting a global problem with representation in the field of archaeology, Sahle actively recruits students from underrepresented groups to participate on his projects. “I give priority to these students because there are certain things that need to change, and I’m happy to contribute to that endeavour,” he says.
However, Sahle says there are moments when he wishes he didn’t follow this path into academia, where he is so often the only Black African in the room. Such was particularly true during his US and European stays as a postdoc and later a research group leader.
But he has come too far to change paths now, or to give up on those who walked the road before him. “I have predecessors who were educated at universities where they were the only African, and represented a negligible minority in the world of palaeoanthropology and archaeology…giants on whose shoulders I must stand,” he says.
“I don’t want to walk away from the problem. I have a purpose to serve, and it may be a challenge, but I believe that together we can change the landscape.”